JPH05302170A - Method and device for liquid-phase cvd - Google Patents

Abstract

PURPOSE:To prevent the infiltration of hydrogen into a film and to obtain a good-quality deposited film in liq.-phase CVD for depositing a material by ultrasonically vibrating the liquefied material. CONSTITUTION:Gaseous O2 is subjected to an electric discharge, the generated O atom is introduced into a chamber 5 through a transport pipe 4, a wafer stage 7 is cooled by a refrigerant, and the depositing material is vibrated by an ultrasonic wave generating means 9 (ultrasonic vibrator). When Si(CH3)4 is introduced under these conditions from a gas inlet 6, the grain is liquefied on a cooled substrate 21 (wafer) and introduced into the minute groove of a high aspect ratio. At this time, the stage 7 is slightly vibrated, hence the substrate 21 is vibrated, the fluidity of the liquefied grain is increased, and the liquefied grain rapidly flows into the groove. The grain is allowed to react with the O atom and oxidized, the oxidation reaction is accelerated by the vibrated liquefied grain, hence a methyl group is not left in the film, and the groove is filled with a good-quality SiO2 film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid phase CVD method for depositing a deposition substance in a liquid phase state and a liquid phase CVD apparatus for performing such a CVD method. INDUSTRIAL APPLICABILITY The present invention can be used for forming a fine thin film or the like in the production of electronic parts (semiconductor devices etc.) and other materials, and in particular, for example, as a thin film forming technique in semiconductor production,
In particular, it can be suitably used for embedding an insulating film in a high aspect ratio substrate and flattening it.

[0002]

2. Description of the Related Art Liquid phase CVD
Technology is drawing attention in the following background. That is, miniaturization and integration are progressing in the field of semiconductor devices and the like. For example, in ultra-LSI devices such as 16-megabit DRAM, it is necessary to integrate more than 30 million elements on a chip of several mm square. For this reason, it has been difficult to integrate such a number of elements by miniaturization of conventional planar elements. Therefore, a groove having a high aspect ratio (height / width) is dug in a substrate such as a Si wafer,
It is necessary to make the structure three-dimensional, such as accumulating (memorizing) charges on this wall. Further, in such a VLSI device,
A multi-layer wiring technique of stacking wiring in double or triple is often used, but in this case, the aspect ratio of the space between the wirings easily exceeds 1. In order to realize such groove-shaped capacitors and multilayer wiring, it is necessary to develop a technology that can evenly bury an insulating film such as a silicon oxide film in a high aspect ratio space and completely flatten the surface. is important.

As a typical flattening technique, a technique of applying etch back after using a flattening coated glass such as SOG, a flattening technique using bias ECR-CVD, and the like are well known.

However, the above-mentioned prior art cannot satisfy the recent demand for perfect planarization accompanying the increase in aspect ratio of device structures. The former technique has problems such as crack generation due to thickening of the SOG film and deterioration of uniformity due to a long etch back time for complete flattening. There are problems of uniformity of horizontal reversion etchback and an increase in the number of steps in which mask alignment is required to remove the protrusions after the horizontal reversion.

In view of these points, recently, liquid phase CVD
The new CVD technology is attracting attention. this is,
The means for depositing a deposited substance via a liquid phase state is used, and the liquid phase CVD technology known so far generally uses a method of liquefying deposited particles in a gas phase on a substrate to be deposited. Let it flow into the groove of the high aspect ratio substrate,
This is a competitive reaction in which oxidation is repeated, and a high aspect ratio substrate is finally embedded to achieve planarization CVD.

As a typical report relating to this, liquid phase CVD using tetramethylsilane (which can be liquid phase CVD at −40 ° C.) (S. Noguchi, H. et al.
Okano and Y. Horike ,: Exte
Ned Abstracts 19th Conf.
Solid State Devices and M
materials, Tokyo, 1987. P451) Cooled plasma CVD using SiH ₄ system (Hirose et al.,
1991 Spring Response 29P-V-11 P633).

[0007] is a technique for filling a groove having a high aspect ratio by liquefying organic particles deposited at a wafer temperature of about -30 ° C using silane and reacting the liquefied particles with O atoms. However, according to this technique, if the liquefaction rate of the deposited particles in the gas phase is faster than the oxidation rate, bubbles will be generated in the film and a porous film will be obtained, according to the reported technique. In some cases, the oxidation reaction does not proceed sufficiently and methyl groups remain in the film, which causes a problem in film quality. Therefore, for example, the pressure resistance may be deteriorated. A technique using tetramethoxysilane as the organic silane has also been reported.

Also, the substrate temperature is -110 ° C.,
This is a technique in which the film-forming precursor made of silane has fluidity by further lowering the temperature and enables filling of a groove with a high aspect ratio. However, this technique has a problem that a large amount of hydrogen is taken into the film because low temperature growth is performed.

Therefore, in the liquid phase CVD technique which enables the embedding of a high aspect ratio substrate, the development of a technique which solves the above-mentioned problems and realizes a CVD of a good film quality is desired.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid CVD method and a liquid CVD apparatus capable of obtaining a good quality deposited film.

[0011]

The invention of claim 1 of the present application is a liquid phase CVD for depositing a deposition substance through a liquid phase state.
A liquid-phase CVD method characterized by comprising a step of applying ultrasonic vibration to a deposited substance in a liquid-phase state, which achieves the above object by this configuration.

According to the invention of claim 2 of the present application, in a liquid phase CVD apparatus for performing liquid phase CVD for depositing a deposition substance in a liquid phase state, ultrasonic wave generating means for applying ultrasonic vibration to a substrate to be deposited is provided. A liquid-phase CVD apparatus characterized in that the above-mentioned object is achieved by this configuration.

The invention according to claim 3 of the present application is characterized in that the ultrasonic wave generating means is an ultrasonic wave vibrator which is any one of a piezoelectric vibrator, an electrostrictive vibrator and a magnetostrictive vibrator. The liquid-phase CVD apparatus described in 1 above, which achieves the above object by this configuration.

In the CVD method of the present invention, the temperature of a deposition target substrate, for example, a semiconductor wafer, is lowered to a temperature equal to or lower than the dew point of the deposition particles in the vapor phase so that the particles are once liquefied.
In the method of forming a solid thin film using this liquefied substance, ultrasonic vibration can be applied to the substrate.

In the CVD method of the present invention, the temperature of a deposition target substrate, for example, a semiconductor wafer, is lowered to a temperature equal to or lower than the dew point of the deposition particles in the gas phase to liquefy the particles once,
In the method for forming a solid thin film using this liquefied substance, an embodiment may be adopted in which a cooling wafer stage in the apparatus has an ultrasonic vibrator built-in or a mechanism for inducing ultrasonic vibration. it can.

[0016]

According to the present invention, the deposited material is ultrasonically vibrated in the liquid phase state, and therefore, the fine vibration satisfactorily penetrates into the fine grooves having a large aspect ratio. Further, the ultrasonic vibration makes it possible to enhance the fluidity of the liquefied deposited substance and improve the filling property in the groove. Therefore, liquid-phase CVD embedding in a more practical temperature range can be realized. In addition, the deposition in a vibrating state results in a dense deposition, so that the quality of the deposited film formed is good. For example, oxidization occurs in the state where the liquefied deposited particles vibrate, and the oxidation reaction also occurs in the conventional liquid phase CV.
As a result of promoting such a reaction, it is possible to suppress the residual of methyl groups, H, etc. in the formed film, remove the cause of deterioration of the film quality, and improve the C of good film quality.
A VD film is obtained. In addition, it is possible to embed a high aspect ratio substrate with good film quality.

Incidentally, Japanese Patent Laid-Open No. 1-298169 discloses that
Although a technique of ultrasonically vibrating the substrate during gas-phase CVD for supplying gas has been shown, the effect of ultrasonic waves on the reaction is small in the gas-phase reaction, and it is difficult to say that the ultrasonic wave contributes significantly. So it's not always effective.

[0018]

EXAMPLES Examples of the present invention will be described below. However, as a matter of course, the present invention is not limited to the examples described below.

Example 1 This example is an example in which the present invention is applied to a discharge chamber separation type liquid phase CVD apparatus and a liquid phase CVD method using the same. The structure of the apparatus of this embodiment is shown in FIG.

In FIG. 1, 1 is a microwave power source, 2 is a gas introduction tube, 3 is a discharge tube, 4 is a transport tube for active species, 5 is a reaction chamber, 6 is a deposition gas introduction section, and 7 is a chiller refrigerant. The supplied wafer stage, 8 is an exhaust port. In the wafer stage 7 of this apparatus, a piezoelectric ultrasonic transducer made of quartz is incorporated as an ultrasonic wave generating means 9, and DC is generated.
The power supply is connected. On the wafer stage 7, a substrate 21 (Si wafer) which is a deposition target substrate is placed.

In the present embodiment, using the above-mentioned device,
Deposition was performed on the substrate 21 as shown in an enlarged view in FIG. The substrate 21 has shallow trench patterns 2a to 2e having an opening diameter of 0.35 μm to 2 μm and a depth of 1 μm, and here, the shallow trench patterns 2a to 2e.
Embedding of e was performed by a liquid phase CVD method using a tetramethylsilane-based gas. The conditions were as follows. Gas used: O ₂ = 2400 SCCM Pressure: 2 Torr μ wave power: 500 W

Under the above conditions, the O ₂ gas was discharged to generate O 2
Atoms are introduced into chamber 5 through transport tube 4. At this time, the wafer stage was cooled to −40 ° C. by the cooling medium, and DC power of 200 W was applied for ultrasonic vibration. The ultrasonic vibration can be applied at a frequency of 15 to 1 MHz, for example, at 1 to 10 W.

In this state, the Si (CH 2
₃ ) Introduce 100 SCCM of ₄ . Introduced Si (CH
₃ ) The ₄ particles are liquefied on the cooled substrate 21 and flow into the trenches which are the shallow trench patterns 2a to 2e.
At this time, the wafer stage 7 generates minute vibrations due to the effect of the ultrasonic oscillator which is the ultrasonic wave generating means 9, and the substrate 2
Since vibration is also applied to No. 1, the fluidity of the liquefied deposited particles is promoted, and the deposited particles flow into the groove more quickly. At this time, the liquefied particles react with the arriving O atoms to proceed with oxidation. In this oxidation reaction, the reaction is further promoted because the liquefied particles are vibrating, and the methyl group remains in the film. Suppressed. As a result, finally, the trench patterns 2a to 2e can be completely filled with a SiO ₂ film having a good film quality, and a good deposition result as shown in FIG. 2B can be obtained. In FIG. 2B, reference numeral 22 indicates SiO ₂ which is a filling material.

Embodiment 2 This embodiment embodies the liquid phase CVD method and liquid phase CVD apparatus of the present invention as a plasma CVD apparatus and a CVD method using the same. FIG. 3 is a schematic sectional view of the apparatus of this example.

In FIG. 3, 31 is a chamber, 32 is a parallel plate RF applying electrode, 33 is a wafer stage cooled by liquid nitrogen, 34 is an exhaust port, and 35 is a gas inlet.

In the wafer stage 33 of this apparatus, a piezoelectric ultrasonic oscillator made of quartz is incorporated as an ultrasonic wave generating means 36, and a DC power source is connected thereto.

In the present embodiment, using the above device,
FIG. 2 is a sample similar to the sample used in Example 1.
The substrate 21 shown in (a) is filled with SiH ₄ / O ₂
I went with the system. The conditions were as follows. Gas used: 3% SiH ₄ inH ₂ / O ₂ = 100/10
SCCM pressure: 0.2 Torr RF power density: 0.44 W / cm ² substrate temperature: -110 ° C

The high-order silane-based highly fluid film-forming precursor formed by RF glow discharge has a higher fluidity due to the effects of low temperature and stage vibration, so that it is in the groove of the substrate 21 of FIG. 2 (a). Flow into. Further, this liquid film-forming precursor is further accelerated in its oxidation reaction due to the effect of vibration, so that the amount of residual H in the film is also suppressed. Therefore, as a result, as shown in FIG. 2B, it was possible to realize the complete filling of the groove with good film quality.

In this embodiment, when a nitrogen-based gas such as N ₂ or NH ₃ is used as the gas, plasma SiN (silicon nitride) can be obtained.

Example 3 Similar to Example 2, an electrostrictive oscillator was used as the ultrasonic wave generating means, and the other conditions were the same as in Example 2. As a result, the same effect could be obtained.

Example 4 The same procedure as in Example 2 was carried out except that an ultrasonic magnetostrictive oscillator was used, and the other conditions were the same as in Example 2. As a result, the same effect could be obtained.

The present invention is not limited to the above-described embodiments, and it is needless to say that it can be further modified. For example, the apparatus structure, film forming conditions, etc. can be appropriately changed without departing from the scope of the present invention. Needless to say.

[0033]

EFFECTS OF THE INVENTION According to the present invention, for example, a liquid capable of obtaining good deposition even with respect to a deposited substrate having a high aspect ratio embedded portion with a flatness higher than in the past and with a deposited film quality higher than in the past. A CVD method and a liquid CVD apparatus can be provided.

[Brief description of drawings]

FIG. 1 is a radical-transporting liquid-phase CVD used in Example 1.
It is a schematic sectional drawing of an apparatus.

FIG. 2 (a) is a schematic sectional view of a substrate sample used in an example of the present invention.

FIG. 2B is a schematic cross-sectional view showing a state after SiO ₂ is embedded in the example of the present invention.

FIG. 3 is a schematic cross-sectional view of a liquid CVD apparatus applied to the plasma CVD apparatus used in Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Microwave power supply 2 Gas introduction pipe 3 Microwave discharge part 4 Radical transport pipe 5 Chamber 6 Deposition gas introduction port 7 Wafer stage 8 Exhaust port 9 Ultrasonic wave generation means (ultrasonic transducer) 21 Deposition substrate (substrate, Si Wafer) 22 Embedded material (SiO ₂ ) 31 Chamber 32 RF application electrode 33 Cooling wafer stage 34 Exhaust port 35 Gas inlet port 36 Ultrasonic wave generation means (ultrasonic transducer)

Claims (3)

[Claims] 1. A liquid-phase CVD method for depositing a deposition substance in a liquid-phase state, comprising the step of applying ultrasonic vibration to the deposition substance in the liquid-phase state. 2. A liquid phase CVD apparatus for performing a liquid phase CVD for depositing a deposition substance in a liquid phase state, characterized by comprising an ultrasonic wave generating means for applying ultrasonic vibration to a substrate to be deposited. CVD equipment. 3. The liquid phase CVD apparatus according to claim 2, wherein the ultrasonic wave generation means is an ultrasonic wave vibrator that is one of a piezoelectric vibrator, an electrostrictive vibrator, and a magnetostrictive vibrator.